Hydraulic pump



979 R. F. VAN ALLEN ETAL 3,496,87

' HYDRAULIC PUMP Filed Nov. 16, '19s? 2 She ets-Sheet 1 F. 24, 1970 R. F. VAN ALLEN Er'AL 3,

HYDRAULIC PUMP Filed Nov. 16, 1967 2 Sheets-Sheet z United States Patent US. Cl. 103-44 6 Claims ABSTRACT OF THE DISCLOSURE A pump mechanism including a reciprocable pump piston in an immersed cylinder for reciprocating fluid to actuate a diaphragm member for pumping other fluid, an inlet check valve to the cylinder carried by the piston, opened on the suction stroke and closed on the pressure stroke, a rotary eccentric cam for reciprocating the piston, means mounting the cam with its axis to one side of that of the piston to reduce side load on the piston, a beveled gear secured to the cam for driving the same, a pinion driving the gear, and means mounting the gear for adjustment on the cam to spread the wear on the gear corresponding to the high pressure position of the piston.

The invention relates generally to fluid pumps and more particularly to a pump in which a diaphragm is used as the pumping element and is operated by a hydraulic fluid between a reciprocating piston and the diaphragm.

It is a general object of the invention to provide a new and improved pump of the type described.

Another object is to provide such a pumping device embodying a fluid reservoir having a piston and cylinder and piston operating means located therein under the fluid level in the reservoir, and an inlet port in the piston controlled by a valve carried on the piston and movable opposite to the piston movements.

Another object is to provide such a pump of simple construction and embodying a drive means for the piston including gearing which has elements relatively adjustable to compensate for wear.

Other objects will become readily apparent from the following detailed description, taken in connection with the accompanying drawings, in which:

FIG. 1 is a vertical section through a preferred form of the invention approximately along line 11 of FIG. 2, and with external parts shown somewhat diagrammatically;

FIG. 2 is a vertical section along line 2-2 of FIG. 1; and

FIG. 3 is a top plan view on a reduced scale.

While there is shown in the drawings and herein described a preferred form of the invention, the scope of the invention will be pointed out in the appended claims.

As shown in the drawings, the invention is embodied in a pump comprising a substantially square hollow casing having side walls 11, 12, 13 and 14, and a bottom 15. A cylinder 16, formed integrally with the wall 11 has a vertical bore 17 in which a piston 18 is slidably fitted.

For reciprocating the piston 18, a cam 19 is rotatably supported by a roller bearing 20 on a stationary shaft 21 secured at its ends 22 and 23 respectively in bores 24 and 25 in the walls 11 and 12. A ring 26 on the periphery of the cam engages the upper end 27 of the piston which is urged upwardly by a coiled spring 28. A beveled gear 29 is secured to the cam 19 by screw devices 30 and may have an additional roller bearing 31 providing support on the shaft 21. A drive gear 32 preferably in the form of a worm engages the gear 29 and is formed on a drive shaft 33 which is transverse to shaft 21 and supported adjacent one end by a ball bearing 34 fitted into a bore 35 in the casing wall 14. The other end 36 of the drive shaft is of reduced diameter and is journalled in a bore 37 in a bracket 38 formed on the casing wall 12. The shaft 33 may be coupled to a suitable drive motor or other drive means (not shown) as by a coupling member 39 keyed to the shaft.

It is contemplated that the casing 10 will be kept substantially full of a suitable fluid, some of which the piston 18, when reciprocating, will reciprocate in a conduit 39 (FIG. 1) and a chamber 40 of a diaphragmtype pump 41. This pump has a casing with a lower portion 42 forming the chamber 40, and an upper portion 43 provided with inlet and outlet check valves 44 and 45 respectively, in inlet and outlet passages 46 and 47. A diaphragm 48 is sealed around its edge between discs on the casing portions 42 and 43 and serves as a pumping member for a fluid above the diaphragm while being actuated by a different fluid below the diaphragm. Ports 49 and 50 are provided in the upper portion 43 of the casing and a plurality of ports 51 are provided in the lower casing portion 42.

It will be readily apparent that the piston 18, when reciprocated by the cam 19 when the cam is driven, will reciprocate the fluid in the cylinder 16 and conduit 39 to cause simultaneous operation of the diaphragm 48 to pump fluid from the inlet passage .46 to the outlet passage 47. The spring 28 serves to move the piston through its upward or return stroke.

Preferably a relief valve 55 is provided between the pressure end of the cylinder 16 and the oil reservoir space 56 in the casing 10, to prevent excess pressure in the cylinder, the conduit 40 and the chamber 41.

To maintain the cylinder 16, the conduit 39 and the chamber 40 filled with fluid, a port 57 is provided in the head end of the piston 18 and a disc-type check valve 58 is located in an enlarged portion 59 of said port. The disc valve is confined in the port by a washer 60 located against the adjacent shoulder 61 in the piston. As shown, the disc valve has a central portion which closes the port 57 during the pressure strokes of the piston 18 and has a plurality of ports 62 which serve "to admit fluid through the port 57 during the upward or suction strokes of the piston when the valve is momentarily unseated from the position shown against ring 26.

The disc valve member 58 provides a precise control of the volume of makeup fluid supplied to the cylinder 16 when the stroke of the disc is properly controlled and the size of the apertures 62 is properly defined. On the one hand, the stroke of the disc should be short enough that the valve closes before there is significant loss of efiiciency on the pumping stroke. On the other hand, the stroke of the disc should be long enough to allow flow of sufficient makeup fluid. At one extreme, the apertures 62 should be small enough to create a pressure drop across the valve disc causing valve closure. At the other extreme, the apertures should be large enough that the flow of fluid through the disc is adequate to satisfy makeup requirements. The makeup fluid required is that volume lost from the system on each pump stroke, primarily past the piston, due to the need to pump some volume slightly greater than the volume to be displaced by the diaphragm, in order to assure full diaphragm movement.

The valve disc 58 is arranged to drop by gravity to a valve open position when not subjected to pressure from the bottom side and this facilitates initial filling of the system. With the disc dropped, the passages 62 are open to permit the flow of fluid into the cylinder 16 and the flow of air out of the cylinder. Because of the curvature of the ring, fluid may enter passage 57 through enlarged entrance 57a. After the system is once filled, and during shut-down between periods of use, leakage of fluid past the piston 16 results in a pressure drop beneath the valve disc 58 permitting the disc to fall to a valve open posltion in which makeup fluid may be admitted through the apertures 62.

During operation of the pump, excessive wear may take place between the gear 29 and gear 32 at a location determined by the times of maximum pressure in the cylinder 16. To provide for more eflicient and complete use of the gear 29, it is herein shown fastened to the cam 19 by three pins 65 and three set screws 30, the pins and set screws each being located 120 degrees apart as viewed in FIG. 2. Thus, by removing the set screws from time to time, the gear 29 may be rotated 120 degrees with respect to the cam 19 and again fastened to the cam to subject less worn portions of the gear to the maximum driving load at peak pressure.

The cylinder 16, as seen in FIG. 2, is positioned with its axis 66 to the right of a vertical plane 67 through the axis of the shaft 21. Thus, with the gear 29 and cam 19 rotating in a clockwise direction, the downward pressure of the cam on piston 18 during the pressure stroke is more directly in line with the axis of the piston and results in minimum side wear of the piston in the cylinder. The ring 26 is confined axially on cam 19 by rings 68 and 69. For the most part, the ring 26 does not rotate with the cam and therefore has primarily a rolling contact with the end of the piston. It is prevented from rotation during most of its contact with piston 18, but will creep slightly on suction strokes. Since the parts are below the level 70 of the fluid in the casing, the fluid is in the form of a lubricating oil and maintains all of the parts properly lubricated. A vent device 71 is provided in the top 72 of the casing and a drain plug 73 at the bottom.

The shaft 21 carries a split ring 74 which backs a thrust bearing 75 for the cam 19 and gear 29. The shaft 1s threaded at 76 and provided with a self-locking nut 77 to facilitate adjustment of the shaft in the casing. A set screw 78 is provided to secure the shaft against rotation in longitudinally adjusted positions. In operation, the thrust of gear 29 and cam 19 is toward the left as viewed in FIG. 1, because of the action of worm gear 32. Such thrust is transmitted by hearing 75 to ring 74, shaft 21, nut 77 and ultimately the housing 12. The shaft 21 is adjustable longitudinally toward the right in FIG. 1 by operation of nut 77 to take up backlash in the gears 29 and 32 on initial assembly and as wear occurs. It will be understood that tightening the nut 77 pulls shaft 21, ring 74 and bearing 75, urging the cam 19 and gear 29 toward worm 32.

During operation, when the input shaft 33 is driven to operate the pumping mechanism, the interaction of the drive gear 32 and the driven gear 29 is such that the shaft 33 is subjected to longitudinal thrust in opposite directions axially of the shaft. More particularly, as seen in FIG. 2, it will be understood that as the gear 29 and cam 19 are driven in a clockwise direction and the high part of the cam approaches the top end of the piston 18, the resistance of the spring 28 and the pressurized fluid under the piston impose a load on the gear 29 such that the gear 29 tends to move the drive gear 32 and the drive shaft 33 toward the right as viewed in FIG. 2 until such time as the high part of the cam passes over center past the piston 18. Immediately after the cam passes over center, the strong bias of the shaft 33 toward the right is relieved and indeed the force of the return spring 28 urges the piston to seek the low part of the cam, thereby tending to rotate the cam and gear 29 in a clockwise direction such that the interlock between the gear 29 and the gear 32 tends to pull the gear 32 and the shaft 33 toward the eft.

In order to mount the shaft 33 for stability longitudinally against the opposed longitudinal thrust forces, the shaft is formed with an annular shoulder 330 adjacent gear 32, a reduced shaft portion 33b to the right of the shoulder, a smaller intermediate shaft portion 33c and a groove 33d. Ball bearing 34 includes an inner race 80 on shaft portion 330 and an outer race 81 in the bore 35 of the casing wall. Longitudinal thrust of the shaft 33 toward the right in FIG. 2 is transmitted to the housing through the outer bearing race 81.

Specifically, the reduced shaft portion 33b has a thrust washer 83 engaging shoulder 33a and backing a needle bearing 84 in turn engaged by a thrust washer 86 abutting outer bearing race 81. The entire bearing structure in the bore 35 is appropriately sealed against leakage of fluid and is retained in place by means of an annular housing 88 surrounding the coupling 39 and secured to the main casing as by screws 89 in a boss 90 surrounding bore 35. The housing member 88 is formed with an annular shoulder 92 engaging the right end of outer bearing race 81. With the arrangement described, it will be understood that longitudinal thrust of the shaft 33 toward the right, as viewed in FIG. 2, is transmitted through shoulder 33a, thrust washer 83, needle bearing 84, thrust washer 86, and outer race 81 to the housing structure.

In order to resist the reverse thrust on the shaft 33, the shaft groove 33d carries a snap ring 94 which engages a collar 95 capturing a resilient O-ring 96 on the shaft portion 33c against the inner bearing race 80. The parts are assembled with the O-ring partially compressed and with the outer rim of the collar 95 slightly spaced from the end of the inner bearing race 80. Outer bearing race 81 is retained against longitudinal movement toward the left as viewed in FIG. 2 by an outer snap ring 97 engaging boss 90 and received in a recess at the end of housing member 88.

In operation, when the shaft 33 is pulled toward the left, the ring 94 in groove 33d abutting collar 95 is resiliently detained by the resilient O-ring 96. The O-ring reacts against the inner race 80, which in turn reacts against the balls of the bearing, which in turn react against the outer race 81 which is grounded against the boss 90 by snap ring 97. Underconditions of normal operation, the resilient ring 96 resists the reverse thrust on the shaft 33. However, to ensure against unusual conditions damaging the resilient ring, as when unusual pulls are exerted on the shaft, the outer rim of the collar 95 is movable into positive stop engagement with the inner race 80. The resilient compressibility of the O-ring 96 facilitates assembly of the completed device without play while allowing some tolerance of dimensions in parts during manufacture.

We claim:

1. A pumping device having, in combination, a casing forming a reservoir, a piston and cylinder device located in said reservoir and below the normal fluid level in the reservoir, a port formed in the cylinder to permit fluid to pass in and out of the cylinder, means for reciprocating the piston, means for supplying fluid from the reservoir to the cylinder to replenish fluid leaking from the cylinder comprising a port in the piston communicating with the interior of the cylinder and with the reservoir, a check valve carried on the piston and movable from an open position during a suction stroke of the piston to a closed position during a pressure stroke of the piston, a spring in said cylinder for moving the piston through its suction stroke, a shaft extending across the casing and across the axis of the cylinder, a cam rotatably supported on said shaft and operable on the piston to actuate it, a driven gear fastened to the cam by means of devices located apart uniform distances to permit the gear to be secured to the cam in any one of a plurality of angularly spaced positions, and a drive shaft carrying a drive gear meshing with the driven gear.

2. A pumping device having, in combination, a casing forming a reservoir, a piston and cylinder device located in said reservoir and below the normal fluid level in the reservoir, a port formed in the cylinder to permit fluid to pass in and out of the cylinder, means for reciprocating the piston, means for supplying fluid from the reservoir to the cylinder to replenish fluid leaking from the cylinder comprising a port in the piston communicating with the interior of the cylinder and with the reservoir, a check valve carried on the piston and movable from an open position during a suction stroke of the piston to a closed position during a pressure stroke of the piston, said means for reciprocating the piston comprising a cam shaft extending across the casing transverse to the axis of the piston, a cam rotatable on the shaft and positioned to drive the piston, a beveled gear fastened to the cam, a drive gear engaging the beveled gear for rotating the latter and the cam, a thrust bearing backing the cam, and means for adjusting the thrust bearing longitudinally to move the beveled gear toward the drive gear to take up backlash.

3. A pumping device as defined in claim 2, wherein the means for adjusting the thrust bearing comprises means for transferring the bearing thrust to the shaft, and means for adjusting the shaft longitudinally including a threaded end thereof projecting from the casing and a nut adjustable on the threaded end and reacting against the casing.

4. A pumping device having, in combination, a casing forming a reservoir, a piston and cylinder device located in said reservoir and below the normal fluid level in the reservoir, a port formed in the cylinder to permit fluid to pass in and out of the cylinder, means for reciprocating the piston, means for supplying fluid from the reservoir to the cylinder to replenish fluid leaking from the cylinder comprising a port in the piston communicating with the interior of the cylinder and with the reservoir, a check valve carried on the piston and movable from an open position during a suction stroke of the piston to a closed position during a pressure stroke of the piston, a spring in said cylinder for moving the piston through its suction stroke, a cam shaft extending across the casing transverse to the axis of the piston, a cam on the shaft positioned to drive the piston, a driven gear fastened to the cam, a drive shaft having an integral helical drive gear engaging the driven gear for rotating the latter and the cam, bearing means mounting the drive shaft including means for positively resisting longitudinal thrust of the drive shaft in one direction during the pumping stroke of the piston and means for resiliently resisting longitudinal movement of the drive shaft in the opposite direction during suction stroke of the piston, the bearing means including a ball bearing for radially supporting the drive shaft and having an inner race and an outer race, wherein longitudinal thrust of the drive shaft during the pumping stroke is transmitted to the casing through the outer bearing race, and wherein the opposite longitudinal thrust of the drive shaft during the suction stroke is transmitted to the casing through the inner bearing race, the bearing balls and the outer bearing race.

5. A pumping device having, in combination, a casing forming a reservoir, a piston and cylinder device located in said reservoir and below the normal fluid level in the reservoir, a port formed in the cylinder to permit fluid to pass in and out of the cylinder, means for reciprocating the piston means for supplying fluid from the reservoir to the cylinder to replenish fluid leaking from the cylinder comprising a port in the piston communicating with the interior of the cylinder and with the reservoir, a check valve carried on the piston and movable from an open position during a suction stroke of the piston to a closed position during a pressure stroke of the piston, a spring in said cylinder for moving the piston through its suction stroke, a cam shaft extending across the casing transverse to the axis of the piston, a cam on the shaft positioned to drive the piston, a driven gear fastened to the cam, a drive shaft having an integral helical drive gear engaging the driven gear for rotating the latter and the cam, hearing means mounting the drive shaft including means for positively resisting longitudinal thrust of the drive shaft in one direction during the pumping stroke of the piston and means for resiliently resisting longitudinal movement of the drive shaft in the opposite direction during suction stroke of the piston, and means for positively resisting longitudinal thrust of the drive shaft in said opposite direction during the suction stroke after limited shaft movement compressing said resilient means.

6. A pumping device having, in combination, a casing forming a reservoir, a piston and cylinder device located in said reservoir and below the normal fluid level in the reservoir, a port formed in the cylinder to permit fluid to pass in and out of the cylinder, means for reciprocating the piston including a cam rotatable about an axis, means for supplying fluid from the reservoir to the cylinder to replenish fluid leaking from the cylinder comprising a port in the piston communicating with the interior of the cylinder and with the reservoir, a check valve carried on the piston and movable from an open position during a suction stroke of the piston to a closed position during a pressure stroke of the piston, a spring in said cylinder for moving the piston through its suction stroke, a cam shaft extending across the casing transverse to the axis of the piston, a cam on the shaft positioned to drive the piston, a driven gear fastened to the cam, a drive shaft having an integral helical drive gear engaging the driven gear for rotating the latter and the. cam, and bearing means mounting the drive shaft including means for positively resisting longitudinal thrust of the drive shaft in one direction during the pumping stroke of the piston and means for resiliently resisting longitudinal movement of the drive shaft in the opposite direction during suction stroke of the piston.

References Cited UNITED STATES PATENTS 999,832 8/1911 Milburn 10344 2,143,573 1/1939 Palmer 74423 2,522,633 9/1950 Phillips 103188 2,650,553 1/1953 Pauget 103213 2,900,839 8/1959 Mackintosh 103-213 3,153,381 10/1964 Holley 10344 3,304,870 2/1967 Growall et al 103-44 2,218,927 10/ 1940 Towler et al. 10=3--l69 FOREIGN PATENTS 231,911 12/ 1958 Australia.

WILLIAM L. FREEH, Primary Examiner US. Cl. X.R. 

